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Condensing Boiler Regulations

It is estimated that around 16% of the world’s annual CO2 emissions come from non-condensing boilers and so in a bid to decrease this the UK implemented a series of condensing boiler regulations.

These regulations, along with a set of guidelines, were issued by the Office of the Deputy Prime Minister in 2010. It means all new boilers installed in a property have to be condensing boilers.

Why you need a condensing boiler

Condensing boilers have two internal heat exchangers which means that the heat lost to the surroundings, especially through the flue, is decreased.

This makes them highly efficient. They also use less fuel and power which makes them the greener alternative, plus their CO2 emissions are much lower than their non-condensing counterparts.

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What the condensing boiler regulations say

In simple terms the new regulations state that:

  • All gas-fired boilers fitted after the 1st April 2005 have to be condensing boilers. This applies to all brand new installations and those that are a boiler replacement.
  • All oil-fired boilers fitted after the 1st April 2007 have to be condensing boilers and again this applies to new installations and replacement boilers.
  • All condensing boilers fitted after the 1st April 2005 have to have a SEDBUK efficiency rating of either A or B.

There are a number of other new regulations in addition to these three, however, these are the main ones that need to be followed.

The exceptions to condensing boiler regulations

In some circumstances it may be very difficult or costly to replace an old non-condensing boiler with a new condensing boiler and in these situations a full assessment has to be carried out. The assessment is based on a points system and the more points a dwelling scores, the more likely it is that a condensing boiler can’t be fitted.

If, following the assessment, it turns out that a dwelling is unsuitable for a condensing boiler then a certificate to say as much has to be issued by a Gas Safe registered technician. This certificate is highly important as it confirms the dwelling’s exemption from the new condensing boiler regulations and it will be needed should the owner decide to sell the house or flat.

Benefits of a condensing boiler

We already know that condensing boilers can reduce the level of CO2 in the atmosphere compared to non-condensing boilers but that’s not the only benefit they offer.


Condensing boilers are 15-30% more efficient than older boilers and even more efficient than the very latest non-condensing boilers.

Lower energy bills

Thanks to their high efficiency, condensing boilers can provide the same amount of energy to your home than non-condensing boilers but by burning less fuel. This means that you won’t be paying as much for your fuel bills and will soon see you making a return on your investment.


A condensing boiler can meet the needs of any homeowner as they have a modern design and compact size which allows them to fit in with the decor and not take up much space. They will often be able to fit into a kitchen cupboard, keeping it out of sight and mind.

Bonus condensing boiler information

Once you have a condensing boiler installed, there are a few things that you’ll need to bear in mind:

  • All new gas-fired and oil-fired boilers have to be condensing boilers and once installed they need to be issued with the Approved Document L1 of the Building Regulations.
  • It is the responsibility of the homeowner to ensure their boiler and heating system complies with the building regulations and so it is vital that all gas boilers are installed by a Gas Safe registered technician and all oil-fired boilers by an OFTEC registered installer.
  • The certificate that is issued will be needed should anything go wrong or should the house be sold in later years.
  • Finally it is also the homeowner’s responsibility to inform the local authority that a new or replacement boiler has been fitted in a particular house.
  • There are a number of new condensing boiler regulations that need to be followed when fitting a new or replacement boiler to your home. A Gas Safe or OFTEC registered installer will be able to explain the regulations and supply you with the certificate you now need by law - whether it is a certificate of compliance or a certificate of exemption.

If you’d like to be contacted by a Gas Safe professional in your area to help with your condensing boiler, we can help.  We have a network of thousands of installers up and down the country all ready to advise you and provide their most competitive quote for the supply and fit of your new boiler.  

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Boiler Guide Team

About the author

Boiler Guide Team

Boiler Guide has been home to a host of heating experts who have helped millions of UK homeowners searching for advice and guidance. If you've got heating questions, we'll have the answers.

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